Improvement in mariners  compasses



G. ILES.

V Mariners Compass.

N0.167,452. Fla I Patented Sept. 7, 1875.

Wflness a)" $766,444, .19- %f% x? I 9 ZZZ- ILFETERS. FHOTO-LIIHOGRAPHER,WISHINGTON o C.

NITED STATES GEORGE ILES, OF MONTREAL, CANADA.

IMPROVEMENT IN MARINERS COMPASSES Specification forming part of LettersPatent No. 167,452, dated September 7, 1875 application filed July 28,1875.

To all whom it may concern:

Be it known that I, GEORGE ILES, of the city of Montreal, in theDistrict of Montreal and Province of Quebec, Canada, have inventedcertain new and useful Improvements in the Adjustment of MagneticNeedles; and I do hereby declare that the following is a full, clear,and exact description of the same.

My invention has reference to means used to ascertain more particularlyin mariners compasses the aberration of any magnetic needle, due tolocal attraction in the ship, its cargo, or machinery, and also for'properly compensating the same, so as to bring the needle to its normalposition.

This invention is designed to supersede the several modes at present inuse for ascertaining the deviation of the needle from the above causesby swinging the ship before leaving port, as it affords an easy andcertain method of finding out and compensating for theconstantly-varying amount of such aberration, not only in port but alsoat any time during the voyage, especially in weather which precludescelestial observationssuch as heavy fogwhen perfect accuracy is mostneeded.

Although my invention is primarily adapted for the purposes ofnavigation, it will be found very useful in land surveying, exploration,and mining, and by suspending the apparatus in a vertical instead of ahorizontal plane it may be used to eliminate errors in the observationof dip.

I will now proceed to describe the construction and operation of myinvention, but for fuller comprehension thereof reference must be had tothe annexed drawings, in which similar letters of reference indicatelike parts, and where- Figure 1 is a plan view of my apparatus. Fig. 2is a vertical sectional elevation of same.

Fig. 3 is a longitudinal section, enlarged, of

needle or longitudinal bar. Fig. 4 is a longitudinal section oftransverse bar. Fig. 5 is a diagram, showing method of compensation.

A is the magnetic needle of any compass, pivoted in any usual mannerupon a metal bar, B, as shown, or upon any ordinary means of support.This needle may be ,of any ap proved construction and conformation; butI prefer to use a thin flat bar of aluminium or any other practicallynon-magnetic metal, to which are suitably fastened, in the line of thebar, any number of small magnets of the best form and magnetized tosaturation, placed as closely together as may be done without undueinfluence upon each other, and having like poles pointing one way. Thisbar must be so constructed that the three planes of division will bisectequal quantities in bulk,

weight and magnetic force, and the reason that it is by preference builtup to carry a large number of small magnets is that the of aluminium orother practically non-mag- I netic metal joined together by transversebars a a of like substance, carrying both on their upper and under sidesthe magnets b, as above described.

D is a bar, of the same metal as above described, pivoted on anysuitable axis concentrieally with the needle A, and being in its normalposition exactly at right angles to it. Upon this bar D are secured anyrequired number of small magnets, d, with like poles pointing one way,placed across the bar as closely together as possible without undueinfluence between themselves. It is absolutely necessary that the amountof the magnetic force in the bar D should be equal to that of needle A,and that in this bar D, also, the three planes of division shall bisectequal quantities in weight, bulk, and magnetic force. Immediately aboveD and at right angles to it is secured a wire, E, of aluminium or likemetal, of equal length with the bar D, and serving for more convenientcomparison with the bar or needle A. The distance between the bar D andneedle A is to be as little as may consistently be left without undueinfluence between them. F F are bell-caps, placed as usual,respectively, above the needle A and bar D to prevent verticalvibration, G being a compass-bowl of any ordinary construction, and hungin the usual way, and H is the dial- FFICE;

plate, divided as usual, and placed most conveniently between the needleA and transverse bar D.

The operation of my invention will be easily understood and may be thusexplained: Presumin g that the cause of disturbance liesin the N. E.,the needle will be deflected in that di rection-z'. a, eastwardly-and.the transverse bar D, which is practically a magnet, pointing E. and W.will also turn toward the disturbing cause, thus making the anglebetween the needle A and bar D in that direction, and the one oppositeto it less than a right angle.

The way in which I propose to compensate for'this attraction and torestore the bar and needle not only to their normal angle of ninetydegrees, but also to their former position, is by means of a steelmagnetic compensator placed, when in use, so that similar or repellingpoles of the compensator and compass are nearest together. Thiscompensator is brought toward the axis of the compass along a'radialline, 1, bisectin g either acute angle until ninety degrees ismarked,therelative movements of the needle A and bar D being noted. Thecompensator is then gradually moved toward the more inert point, ninetydegrees beingmaintained until lines drawn from center of repulsion(marked (J) to each of the two immediately affected halves of the barsshall be 'found to correspond as the square root of the originalaberration of such pointl Thus, if N. has been found to have beendisturbed before compensation four degrees and E. one degree, the centerof compensator must be joined by lines of the proportions shown by Y andZz'. 6., as l and 2-drawn perpendicularly to the two bar halves.

This devicemay be used in combination with any approved form of compass,and, if

desired, the bars may be made hollow and immersed in spirit, as inRitchies compass.

' It must be clearly understood that 1 do not propose to ascertain andcompensate for the deviation of the magnetic needle due to earthcurrentsor other cosmical influence; but

What I claim as my invention, and wish secured by Letters Patent, is-

1. In combination with any magnetic needle the transverse bar D,carrying many minute magnets placed with like poles one way, and beingpractically a magnet pointing E. and W., attracted toward a piece ofiron like an ordinary magnetic needle, as shown and described.

2. In combination with any compass the longitudinal bar carrying manyminute magnets of like poles pointing one Way, and acting as a magneticneedle, as shown and described.

3. In any compass the combination of the longitudinal bar A andtransverse bar D equally attracted by any object, substantially -A andbar D, a compensator, of iron or steel, operating in the mannerdescribed, and for the purposes set forth.

Montreal, 22d day of July, A. D. 1875.

GEORGE ILES.

Witnesses:

NV. DEM. MARLER, FRAS. HY. REYNOLDS.

